Unitary controlled memory hermetic terminals



Jan. 19, 1965 R. u. CLARK 3,166,634

UNITARY CONTROLLED MEMORY HERMETIC TERMINALS Filed Jan. 25. 1964' Fig. l

Fig. 2

INV EN TOR.

Macaw;

United States Patent Filed Jan. 23, 1964, Ser. No. 339,723 2 Claims. (Cl. 174-453) The present invention has to do with hermetic electric terminals such as may be used for passing electric current into and out of a sealed container. The present novel terminal is of the confined gasket type but without having any non-conductive resilient members attached thereto. It may also be described as a unitary device since it has but three preassembled co-operating parts all of which act together to comprise a complete unit.

One of the objects of the present invention is to provide a terminal device that may be mounted in a hole in a panel irrespective of the panel thickness within a wide range of values. This is a definite advantage over prior types which require special reworking for use in panels that are thicker than about one-sixteenth of an inch.

Other advantages of the present device are quick assembly capabilities, high permissible operating temperature and very low electrical loss characteristics. In the present invention the aforementioned objects are achieved by a novel co-operation between the insulating and conductive members of the terminal.

In its simplest form a metal electrode is inserted axially into a through hole in a polytetrafluoroethylene insert or grommet, said grommet thus being of a special type of plastic having a high elongation capability. This high elongation factor is very important since in order to correctly fit the terminal into a given panel it is necessary to subsequently compress the insert member to a very considerable degree. In this connection I have found that material having an elongation factor of at least two hundred percent or better is required in order that the various terminal parts may co-operate in such a manner as to form a satisfactory hermetic terminal.

In addition to the foregoing characteristic it is desirable, but not absolutely necessary, to reinforce the plastic member with some sort of a flexible, but relatively nonstretching, material. This is required to prevent excessive cold flow. The manner in which these already mentioned characteristics of the insulating material used play a part in the achievement of my new type of hermetic terminal will become apparent and be more fully explained in what follows. 7

The reinforcing material just referred to may be of a filament-like nature such as very fine glass fibres or other strong non-conductive filaments, and may comprise by volume from ten to forty percent of the volume of the basic plastic.

In addition to the two co-operating parts already mentioned as forming a part of the terminal a third element in the form of a push-on nut is included in the assembly. This nut is used on the non-flanged end of the plastic member and rides on the electrode and has metal teeth,

at the point where it rides on the electrode, said teeth being positioned away from the plastic member rather than directly adjacent to it.

The electrode that is used in the present terminal incorporates a flange member which in use abuts the flange on the plastic member. I have found that this electrode flange should be made so as to provide spring tension to the whole terminal assembly after it has been correctly mounted into the hole in the panel or case with which it is to be used as an hermetic feed-through. I have found that this spring characteristic in the electrode flange is important since the plastics best suited to this type of terminal do not have much rebound or resiliency.

The terminal of the present invention is mounted in a suitable snug fitting hole in a metal panel or the like by simply inserting the smaller diameter end and pushing the device into the panel until the flange stops further progress. At this point the push-on nut which is resting against the end of the plastic insert is forced in the direction of the flange with a pressure sufficient to expand the Plastic adjacent to the push-on nut to the point where a very firm mounting of the terminal in the panel results. During this operation a suitable tool is used to hold the plastic flange firmly against the panel.

When this terminal configuration is distorted during assembly there is a natural tendency for the plastic to push back against the push-on nut due to memory in the plastic. This action is necessary in order to force the teeth of the nut into the electrode shank to a sufficient extent to form a lock in action under tension. This in turn keeps the plastic insert tightly seated and in sealing relation with the panel.

Some plastic materials that I may desire to use may not have suflicient rebound after compression to cause the teeth of the push-on nut to bite securely into the terminal electrode shank and under these conditions I have discovered that by making my electrode flange so as to provide a degree of spring tension to the assembly that I can produce a terminal that can be firmly mounted in a panel.

Turning now to the drawings which form a part of this application FIGURE 1 is an elevational view of my novel terminal, FIGURE 2 a longitudinally cut away view of the insert used with the terminal, and FIGURE 3 is a view of the electrode alone to show one form of spring type flange that I may employ.

Referring again to the drawing there is shown in FIG- URE 1, the elevational view of the terminal, an electrode 1 having a flange 4 and a notched area 5 suitable for a wire wrap connection. There is also shown a plastic insert at 6 having a flange 2, and a push-on nut 3 which rides on the electrode just clearing the notch 5 and abutting the non-flanged end of the plastic insert, said insert having plastic memory.

FIGURE 2 shows identical parts except that the plastic insert is shown in cross-section in order to expose the shank of the electrode more completely.

FIGURE 3 is drawn to show the flange member of the terminal electrode to have a spring configuration after the nature of a convoluted diaphragm.

It will be obvious to those skilled in the art of terminal attachments that other types of spring flanges may be used, or that an excess amount of spring may be incorporated in the push-on nut to give the desired degree of rebound for correct tooth dig-in after the compression required for the terminal assembly is released.

Having described my invention, I claim:

1. An hermetic electric terminal comprising in combination three elements only, an integral circumferentially flanged terminal electrode, a non-conductive flanged nonresilient insert and a push-on nut, said electrode being fitted axially and concentrically into said insert, the said electrodeflange and the said insert flange being in abutting relationship and the said push-on nut riding on the elec- 3, trode at the insert end away from said insert flange, the non-conductive insert being of a material having an elongation factor of at least two hundred percent, a limited memory produced by included reinforcing filaments, and a restricted cold flow tendency. V

2. A terminal as in claim 1 in which the terminal electrode flange is made in the form of a convoluted diathe length of the electrode structure.

UNITED STATES PATENTS Tyzack May 15, 1956 Clark July 31, 1962 FOREIGN PATENTS Great Britain Mar. 26, 1952 Canada June 24, 1958 

1. AN HERMETIC ELECTRIC TERMINAL COMPRISING IN COMBINATION THREE ELEMENTS ONLY, AN INTEGRAL CIRCUMFERENTIALLY FLANGED TERMINAL ELECTRODE, A NON-CONDUCTIVE FLANGED NONRESILIENT INSERT AND A PUSH-ON NUT, SAID ELECTRODE BEING FITTED AXIALLY AND CONCENTRICALLY INT SAID INSERT, THE SAID ELECTRODE FLANGE AND THE SAID INSERT FLANGE BEING IN ABUTTING RELATIONSHIP AND THE SAID PUSH-ON NUT RIDING ON THE ELECTRODE AT THE INSERT END AWAY FROM SAID INSERT FLANGE, THE NON-CONDUCTING INSERT BEING OF A MATERIAL HAVING AN ELONGATION FACTOR OF AT LEAST TWO HUNDRED PERCENT, A LIMITED MEMORY PRODUCED BY INCLUDED REINFORCING FILAMENTS, AND A RESTRICTED COLD FLOW TENDENCY. 